RU2442768C2 - For separating and purification of 1,3-butadiene from c4-carbohydrate mixtures - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention refers to the method of separating and purification of 1,3-butadiene from the mixture consisting mainly of C₄-carbohydrates and containing 1,3-butadiene and C₄-carbohydrates that differ from the former by the number of unsaturated bonds and/or α-acetylene protons including at least (an) area(s) of extractive rectification with the polar extractant, denudation and ordinary rectification that is characterized by the fact that at least a polar spirit with the boiling point over 120°C is used as the mentioned extractant; stripping of C₄-carbohydrates from the areas of extractive rectification and denudation of the mentioned extractant is performed under the high pressure from 3.5 to 6.5 at, at least into the lower part and/or into the boiler(s) of the extractive rectification area(s) the carbohydrate intermediate desorbent with the boiling point from 27 to 85°C is introduced in the amount that provides its content in the cube(s) of the high pressure denudation area(s) from 3 to 30 % weight; then the intermediate desorbent is stripped from the greater part of the extractant in the low pressure denudation area with 1.0-2.0 at; the extractant is fed back to the upper part of the extractive rectification area(s) and the intermediate desorbent to at least the mentioned point(s) of extractive rectification, and 1,3-butadiene undergoes additional purification from chemical impurities by means of rectification, supposedly with the small amount of extractant.

EFFECT: reduction of losses of 1,3-butadiene and improvement of the processing and economical efficiency.

10 cl, 3 tbl, 3 ex, 3 dwg

Description

The invention relates to the field of separation and purification of 1,3-butadiene from mixtures of predominantly C ₄ -hydrocarbons containing 1,3-butadiene and C ₄ -hydrocarbons, differing from it in the number of unsaturated bonds and / or α-acetylene protons. More specifically, the invention relates to the field of isolation and purification of 1,3-butadiene using extractive distillation, desorption, conventional rectification and optionally selective hydrogenation of α-acetylene hydrocarbons.

Known methods [H. Ulmann, Encyklopädia der Technischen Chemie, 4-th Edition, 1975, vol.9, p.1-18; S. Ogura, T. Onda, Advances in C ₄ -Hydrocarbons Processing; AIChE National Meeting, 1987, Aug., 16-19; P.A. Kirpichnikov, V.V. Beresnev, L.M. Popova. The album of technological schemes of the main industries of the UK industry. L .: Chemistry, 1986, p.14-35] the separation of C ₄ -hydrocarbons, differing in the number of unsaturated bonds by extractive distillation in the presence of polar organic or mixtures thereof with water, followed by desorption of more unsaturated hydrocarbons from the extractant.

Known methods [P.A. Kirpichnikov et al., Ibid., P.23-35; S.Yu. Pavlov. Isolation and purification of monomers for synthetic rubber. L .: Chemistry, 1987, pp. 93-104] isolation and purification of 1,3-butadiene from mixtures containing 1,3-butadiene and C ₄ -hydrocarbons, differing from it in the number of unsaturated bonds and / or α-acetylene protons , by double extractive distillation with a polar extractant and subsequent rectification of 1,3-butadiene, first from propine, which is removed with distillate, and then from α-acetylenes C ₄ and methylallene, which is removed as a part of the bottom residue.

Acetonitrile, methoxypropionitrile, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N-formylmorpholine, sulfolane and their mixtures with a small amount (up to 10% wt.) Of water are proposed as polar extractants for the indicated extractive rectification. A drawback of acetonitrile (T _boiling point 81.6 ° C) is the formation of azeotropes with C ₄ hydrocarbons, from which acetonitrile usually has to be washed with water and then isolated by distillation from aqueous solutions.

High boiling polar solvents do not form azeotropes with C ₄ hydrocarbons, however, industrial processes for the isolation and purification of 1,3-butadiene with high boiling extractants have another significant drawback. When desorbing C ₄ hydrocarbons from them with condensation with the usual available refrigerant - circulating water (~ 20-25 ° C) - it is impossible to use the high pressure necessary for condensation (4-5 ata), since the boiling point of such extractants is excessively high (more than 200-250 ° C) and with it there is a significant decomposition of these polar solvents. In addition, inaccessible heating agents are required.

According to the above sources, when working with high-boiling extractants, a relatively low (1-1.5 ata) pressure in the strippers is usually used and the desorbed hydrocarbons are compressed. However, the use of compressors is associated with their relatively rapid wear and frequent breakdowns, especially when compressing the easily polymerizable 1,3-butadiene.

A common disadvantage of the above methods for the isolation and purification of 1,3-butadiene are its significant (5-8% rel.) Losses due to the need to dilute α-acetylene streams in accordance with safety requirements. The separation of 1,3-butadiene from butenine by conventional distillation is practically impossible and the industrial schemes used include the purification of 1,3-butadiene by second extractive distillation. Further, it is purified by conventional distillation, respectively, of propine and 1-butine and methylallylene. This leads to a complication of the circuit and increased consumption of energy.

We have found technical solutions that allow the elimination of compressors during the isolation and purification of 1,3-butadiene, significantly reduce the loss of 1,3-butadiene and increase the technological and economic efficiency of the processes.

We declare:

1. The method of isolation and purification of 1,3-butadiene from a mixture of predominantly C ₄ hydrocarbons containing 1,3-butadiene and C ₄ hydrocarbons, differing from it in the number of unsaturated bonds and / or α-acetylene protons, including at least a zone (s) extractive distillation with a polar extractant, desorption and conventional distillation, characterized in that at least a polar organic solvent with a boiling point above 120 ° C is used as said extractant, the C ₄ hydrocarbons are distilled off from said extractant from zones e hydrocarbon intermediate desorbent with a boiling point from 27 to 85 ° C is introduced into the process of distillation and desorption at high pressure from 3.5 to 6.5 atm, at least in the lower part and / or in the boiler (s) of the zone (s) of extractive distillation the amount providing its content in the cube (s) of the zone (s) of high-pressure desorption from 3 to 30% wt. the intermediate desorbent is then distilled off from the majority of the extractant in the low pressure desorption zone at 1.0-2.0 atmospheres, the extractant is recycled to the top of the extractive rectification zone (s) and the intermediate desorbent at least to the indicated extractive rectification point (s) and 1,3-butadiene is further purified from impurities by rectification, possibly in the presence of a small amount of extractant.

As additional methods that contribute to the most effective implementation of the method according to claim 1 of the formula, we also declare methods, characterized in that:

said polar solvent is selected from the group consisting of N, N-dimethylformamide, N-methylpyrrolidone, N, N-dimethylacetamide, N-formylmorpholine, sulfolane, methoxypropionitrile or mixtures thereof, possibly with water, and said intermediate desorbent is selected from the group consisting of isopentane , n-pentane, pentenes, cyclopentane, hexanes, hexenes, cyclohexane and mixtures thereof;

- butane (s) and butenes are separated from 1,3-butadiene in the distillate of the extractive distillation zone, for the most part of the separation elements of which the concentration of said extractant is maintained from 60 to 85% by weight;

- from the lower part of the desorption (s) zone (s) of high pressure, a steam stream is withdrawn from the side, including at least α-acetylene hydrocarbons, methylallene and an intermediate desorbent, a part of the stream is concentrated and returned to the specified desorption zone and the rest is removed from the system;

- in the upper part of the desorption zone of high pressure serves an additional amount of extractant and maintain its concentration on most of the separation elements of at least 40% wt .;

- maintain the temperature in the cube (s) of the zone (s) of extractive rectification from 90 to 140 ° C, in the cube (s) of the zone (s) of high pressure desorption from 120 to 170 ° C and in the cube of distillation of the intermediate desorbent from the extractant from 120 to 170 ° C;

- purification of 1,3-butadiene from impurities of α-acetylenes C ₄ and methylallylene is carried out by distillation in the presence of a small amount of extractant, which is introduced into the upper part of the distillation zone and maintain its concentration on most separation elements from 15 to 40% wt .;

- C ₄ hydrocarbons are distilled off from the bottom residue of the indicated rectification zone in the presence of a small amount of extractant and the remaining part is sent to the specified high-pressure desorption zone directly or through its boiler;

- before supplying the initial hydrocarbon mixture to the extractive distillation zone, at least propine and other C ₃ hydrocarbons are separated by rectification by rectification;

- before the initial hydrocarbon mixture is fed into the extractive rectification zone, it is possible, after rectification, from at least propine and other C ₃ hydrocarbons, to catalytically hydrogenate butenin and partially other α-acetylene hydrocarbons to a residual butenin content of 0.01 to 0.2% wt.

Used separation columns may contain various mass transfer plates or other mass transfer devices, for example a nozzle.

In addition to supplying the extractive distillation zone to the lower part and / or the boiler, an intermediate desorbent can also be supplied to the lower part (s) of the high-pressure stripper (s).

To suppress the undesired polymerization of 1,3-butadiene in the separation system, appropriate polymerization inhibitors are introduced into the extractant and / or distillation columns, for example, sodium nitrite into the extractive distillation zone and phenolic and / or nitrogen compounds into distillation columns. To suppress the hydrolysis of some of the extractants, neutralizing agents are introduced, and carbonic compounds decomposing formic acid are introduced into the system with N, N-dimethylformamide.

In order to prevent accumulation of impurities of salts, dimers and oligomers of 1,3-butadiene and butenine, etc. in the extractant, a small part of the extractant (usually 0.5-2% rel.) Is removed for purification, which is carried out by known methods, for example, distillation and / or azeotropic distillation with water, taking into account the specifics of the extractant, and the purified extractant is returned to the system.

To save energy, the heat of the hot streams is used to heat or vaporize the colder streams. For example, in columns of extractive distillation or distillation with a small input of extractant, “blank” (liquid) plates are installed in places with a lower temperature, from which the liquid is supplied for heating (boiling) using a hot stream of extractant or other coolant, after which the vapor forms The liquid mixture returns to the bottom of the column.

The use of the invention is illustrated by the figures (figures) 1-3 and examples. These figures and examples do not exhaust all possible options and other methods can be used, subject to the signs specified in claim 1.

According to figure 1, the initial hydrocarbon mixture is introduced through line 1, evaporated and fed into the extractive distillation column 10 through line 2. The cooled polar extractant (PE) is fed through line 3 to the upper part of the column 10. An intermediate desorbent (PD) and possibly C ₄ hydrocarbon recycling through line 6 are introduced into the lower part and / or the boiler of column 10 along line (s) 4 and / or 5.

A distillate, consisting mainly of butanes and butenes, is withdrawn from column 10 through line 7. A liquid side stream is withdrawn along line 8 from the bottom of the column 10, passed through a heat exchanger (boiler) and returned in a vapor-liquid state to the column 10. Also, a liquid stream is passed from the bottom of the column 10 along line 9, which is passed through the boiler and into the steam - liquid state is returned to the column 10. On the line 11 from the column 10 withdraw the bottom stream, consisting mainly of PE, PD, 1,3-butadiene and impurities.

The specified stream 11 is fed into the high pressure stripping zone 20. It is possible that a stream consisting mainly of the indicated PD is also fed to zone 20 along line 12.

From the top of zone 20, a stream consisting mainly of 1,3-butadiene and impurities is discharged along line 13. A side stream may be removed from zone 20 along line 14, part of it is condensed and returned to zone 20. The rest, containing α-acetylene hydrocarbons and diluent (s), incl. PD, withdrawn through line 16. From the lower part of zone 20, through line 17, a liquid stream is withdrawn to the boiler and then, in the vapor-liquid state, is returned to zone 20.

From the bottom of zone 20, a stream consisting of PE and PD is discharged along line 18. This stream is fed to the low pressure desorption zone 30.

From the top of zone 30, steam stream 19, consisting mainly of PD, is discharged along line 19. The stream is condensed, part of the condensate is returned to zone 30, and the other part is transported along line 21 and fed through line 4 to column 10 and / or through line 5 to its boiler. Perhaps part of the stream 21 is fed through line 12 to zone 20.

From the lower part of zone 30, a stream is discharged via line 22, which is boiled and returned in a vapor-liquid state to zone 30. From the cube of zone 30, a stream mainly consisting of PE is discharged through line 23. It is recycled through heat exchangers and fed through line 3 to column 10.

According to figure 2, the column 10 operates similarly to that shown in figure 1 and the flows have the same numbers up to number 11. The bottom residue of the column 10 through line 11 serves in the middle or lower part of the zone 20, combining the functions of extractive distillation and high pressure stripper. A stream consisting mainly of PE is supplied to the upper part of zone 20 via line 12. Perhaps in the zone 30 on line 13 serves a stream containing mainly PD.

From the top of zone 30, a distillate containing mainly 1,3-butadiene is removed via line 14.

From zone 30, steam side stream is withdrawn via line 15. Part of it is condensed and returned to zone 30. Line 16 removes the stream, which contains mainly α-acetylenes, methylallen and diluent (s). From the lower part of zone 30, a stream is removed via line 17, which is passed through a boiler and returned to the cube of zone 30 in a vapor-liquid state. Based on line 18, a bottom residue containing mainly PE and PD is withdrawn and sent to the lower pressure stripping zone 40 .

A distillate, containing mainly PD, is withdrawn from zone 40 along line 19. The specified distillate is fed into the column 10 through line 4 and / or into its boiler via line 5. Perhaps a part of the distillate is fed into zone 30 (via line 13) and / or its boiler.

A liquid stream is withdrawn from zone 40 along line 21 and returned to zone 40 through a boiler in a vapor-liquid state.

From zone 40, bottoms are withdrawn from line 40 via line 22, mainly containing possibly partially intermediate desorbent. Part of it on line 23 is fed to heat exchangers and then on line 3 to column 10, and the other part on line 12 is fed to zone 20.

According to Fig. 3, the initial hydrocarbon mixture is fed through line 1 to a distillation column 10. From the column 10, through line 2, a distillate is removed containing at least propine and diluents. Line 3 displays the bottom residue containing heavy substances. Line 4 displays the main hydrocarbon stream.

Alternatively, the specified stream or part thereof is fed through lines 5 and 9 to the column 30.

Alternatively, this stream (or part thereof) is fed via line 6 to zone 20 to hydrogenate a portion of α-acetylenes, in particular butenin, in it. Via line 7, hydrogen is supplied to zone 20. From zone 20 along lines 8, 9 and a heat exchanger (evaporator), the hydrocarbon stream from zone 20 is fed to column 30.

In the upper part of the column 30 along the line 11 serves a stream containing mainly PE. In the lower part of the column 30 or / and its boiler, flow (s) containing (e) predominantly PD are supplied through line (s) 12 and / or 12 '. Perhaps along the line 13 in the column 30 serves part of the distillate from zone 40.

From the column 30, a distillate is removed via line 14, which contains mainly butanes and butenes. From the lower part of the column 30, liquid side streams are removed via lines 15 and 16, which are heated and returned to the column 30 in the vapor-liquid state. The bottom residue, containing mainly PE, PD, 1,3-butadiene and impurities, is withdrawn from line 17. It is fed through line 18 to the high-pressure stripping zone 40. It is possible that a stream containing mainly PD is fed through line 19 to the lower part of zone 40.

From the top of zone 40 along line 21 and possibly along line 22, stream (s) containing (e) predominantly 1,3-butadiene and impurities: α-acetylenes and methylallen are withdrawn. Stream 21 is fed to distillation zone 70.

It is possible that a vapor stream including C ₄ α-acetylenes and diluents is fed through line 23 and fed to an additional high-pressure stripper 60. From the top of stripper 60, stream (s) containing (e) are output via line (s) 24 or / and 24a α-acetylenes C ₄ , methylallen and diluents.

From the lower part of zone 40, a liquid stream is discharged along line 25, containing mainly PE and PD. This stream is connected to the liquid stream from the bottom of stripper 60 (line 38), passed through a boiler and part of the resulting vapor-liquid stream is returned to zone 40, and its other part is fed to stripper 60. From the bottom of zone 40, a liquid stream containing mainly PE and PD, and along line 26 direct it to the low pressure desorption zone 50.

At the top of zone 50, a steam stream containing mainly PD is discharged via line 27, it is condensed, a part of the condensate is returned to zone 50, and the rest is distributed into parts that are supplied to zone 30 via line (s) 12 or / and 12 ', the lower part of the distillation column 70 along line 31 and possibly to the lower part or boiler of zone 40.

From the lower part of zone 50, a liquid stream is discharged via line 28, which is heated and returned to the zone 50 in a vapor-liquid state. From the cube of zone 50, a stream containing mainly PE is discharged along line 29, part of which is directed to lines at the top of lines 32 and 11 part of the column 30, and the other part along the line 33 serves in the upper part of the column 70.

From the top of column 70, distillate containing pure 1,3-butadiene is removed from line 34. From the bottom of the column 70, liquid streams are discharged along lines 35 and 36, which are heated and returned to the column 70 in the vapor-liquid state.

From the cube of the column 70, a liquid stream is withdrawn via line 37, which is supplied to the column 60.

In all the examples cited: F _in — initial hydrocarbon mixture, F — feed to specific zones, D — distillate (s), B — bottoms (e) residue (s), ER — extractive distillation, VD — high-pressure desorption, ND — low pressure desorption, ME — rectification with a small supply of extractant, N — number of plates, R — reflux ratio; all concentrations in% wt.

Example 1

The process is implemented according to figure 1. Lines 6, 12, 14, 15, 16 are not used. The initial mixture is a C ₄ -carbon fraction of pyrolysis. Polar extractant - N, N-dimethylformamide (DMF), intermediate desorbent - n. pentane. The concentration of the extractant in the middle zone of the ER - 70% wt.

The characteristics of the main flows and process parameters are given in table 1.

Example 2

The process is implemented according to figure 2. The initial mixture is a C ₄ hydrocarbon fraction of pyrolysis. The polar extractant is N, N-dimethylformamide (DMF), the intermediate desorbent is a mixture of n. pentane and n. hexane (2: 1). The concentration of the polar extractant in the middle part of the column is 10-70% wt., In the upper part of the zone (below input 12) 20-60% wt.

The characteristics of the main flows and process parameters are given in table 2.

Example 3

The process is implemented according to figure 3. The initial mixture is a C ₄ -carbon fraction of pyrolysis. In zone 20, a "Pd solid support" hydrogenation catalyst is used. As a polar extractant is used N-methylpyrrolidone with 2% wt. water. Intermediate desorbent - electrical tape. The concentration of the polar solvent (extractant): in the middle part of the column 30 is 70% wt., In the middle of the column 70 is 25-27% wt.

The characteristics of the main flows and process parameters are given in table 3.

Table 1 for example 1 Components (% wt.) And parameters F _in lin. one Ext, rect. (Col 10) VD desorption (zone 20) ND desorption (zone 30) D lin. 7 B lin. eleven D lin. 13 B lin. eighteen D lin. 21 B lin. 23 C ₃ hydrocarbons (incl. Proin) 0.7 (0.2) 0.9 (~) - 0.03 ~ 0.45 - - - butanes 9.5 17,2 - - - - - isobutene 23,4 42,4 - - - - - 1-butadiene 12,4 22.5 - - - - 2-butenes 9,4 16.5 0.05 cis-2-bi 0.61 - - - 1,3-butadiene 43.0 0.5 7.5 95.36 - - - methylallen 0.2 - 0,03 0.45 - - - 1-butine 0.2 - 0,03 0.45 - - - butenin 0.7 - 0.14 1,56 - - - C ₅ in f _in 0.5 - 0.12 1.12 - - - desorbent PD - - 6.90 - 7.5 95.0 0.6 extractant - - 85,20 - 92.5 5,0 99,4 Σ kg / hour 100.0 55.2 569.2 44.8 524.4 38.3 486.1 N (practical) 150 fifty 20-30 E / Fugl. Wt. 4.83 - - Top pressure, ata 4.0-4.5 4.0-4.5 1.0-1.1 Temperature (° C):. Top ~ 40 ~ 40 ~ 40 cube 115-120 160 150-160

Table 2 for example 2 Components (wt.%) And parameters F _in lin. one ER-1 Zone 20 (ER -2) VD-desorption (zone 30) ND desorption (Col. 40) D lin. 7 B lin. eleven D lin. fourteen Side. selection, lin. 16 B lin. eighteen D lin. 19 (flows 4/13) B lin. 22 (threads / 12) C ₃ hydrocarbons (incl. Propine) 0.7 (0.2) 0.9 (~) ~ 0.03 0.005 0.2 - butanes 9.5 17,2 - - - - isobutene 23.4 42,4 - - - - 1-butene 12,4 22.5 - - - - 2-butenes 9,4 16.5 0.05 pis-2-bn 0.05 - - 1,3-butadiene 43.0 0.5 7.5 99.07 9.7 - methylallen 0.2 - 0,03 0.02 7.3 - 1-butine 0.2 - 0,03 0.003 9.7 - butenin 0.7 - 0.14 0.002 34.1 - C ₅ in f _in 0.5 - 0.12 19.5 0.02 0.1 - desorbent PD - - 6.90 - 19.5 7.43 95.0 0.6 extractant - - 85,20 - 92.56 5,0 99,4 Σ kg / hour 100.0 55.2 569.2 42.95 -2.05 628.3 45.7 (37.9 / 7.8) 582.6 (486 / 96.6) N (practical) 150 40-45 40-45 20-30 E / F, wt. 3.83 2.18 ~ Top pressure, ata 4.0-4.5 4.0-4.5 4.5-5.0 1.0-1.1 Temperature (° C):. Top ~ 40 ~ 40 cube ~ 115-120 160 155-160

Table 3 for example 3 Components (wt.%) And parameters F _in L. 1 Rectification Number 10 Zone 20 out. ER-1 Number thirty VD desorbts. Zone 40 ND desorbts. Zone 50 VD des. 3.-60 ME-rect. Count 70 D L. 2 B L. 3 Side. L. 4 L. 8 D L. 14 B L. 17 D L. 21 B L. 26 D L. 27 B L. 29 D L. 24 D L. 34 B L. 37 C ₃ hydrocarbons (including propine) 0.7 (0.2) 35.0 (10.0) - 0,0002 0,0005 - - 0.001 - - - - 0.001 - butanes 9.5 35.0 15.4 8.9 9.1 16,2 - - - - - - - - isobutene 23.4 15.0 - 23.9 23.8 42,4 - - - - - - - 1-butene 12,4 10.0 - 12.6 13.0 23,2 - - - - - - - 2-butenes 9,4 ~ 23.0 9,4 10.1 17.6 0.05 0.71 - - - 2.0 0.7 0.01 1,3-butadiene 43.0 5.0 15.4 44,2 43.7 0.6 7.71 98.83 - - - 38,0 99.3 0.25 methyl allen 0.2 7.7 0.1 0.08 - 0.014 0.18 - - - 14.0 0.01 0.09 1-butane 0.2 0.2 0,07 - 0.012 0.16 - - - 14.0 0.001 0.09 butenin 0.7 0.7 0.05 - 0.009 0.12 - - - 10.0 0.002 0.06 C _5- angle In f _in 0.5 - 38.5 0.05 - - - - - - - - - - desorbent PD - - - - - - 6.91 - 9.2 95.0 0.6 22.0 - 19.85 extractant - - - - - - 85.30 - 90.8 5,0 99,4 - - 79.65 Σ kg / hour 100.0 2.0 1.3 96.7 96.7 54,2 548.3 42.5 584.5 53.1 * 531.4 * 0.5 42.1 79.1 N (practical) 70-80 150 40-50 20-30 40 70-80 E / F, wt. - 4.8 Top pressure (ata) 5.0-5.5 4.0-4.5 4.0-4.5 1.0-1.2 4.0-4.5 4.0-4.5 Temp. (° C): top 40-45 twenty-
thirty 40-45 40-45 35-45 40-45 40-45 cube ~ 60 105-115 ~ 160 ~ 160 ~ 160 130-140 * - flow ratios: item 11 / item 33 = 468/63, item 12 (12 ') / item 31 = 63.0 / 15.7.

Claims (10)

1. Method for the isolation and purification of 1,3-butadiene from a mixture of predominantly C ₄ -hydrocarbons containing 1,3-butadiene and C ₄ -hydrocarbons, differing from it in the number of unsaturated bonds and / or α-acetylene protons, including at least a zone (s) extractive distillation with a polar extractant, desorption and ordinary distillation, characterized in that at least a polar organic solvent with a boiling point above 120 ° C is used as the specified extractant, C ₄ hydrocarbons are distilled off from the specified extractant from the zones extractive distillation and desorption at high pressure from 3.5 to 6.5 atmospheres, at least a hydrocarbon intermediate desorbent with a boiling point of 27 to 85 ° C is introduced into the lower part and / or into the boiler (s) of the extractive distillation the amount ensuring its content in the cube (s) of the high-pressure desorption zone (s) from 3 to 30 wt.%, the intermediate desorbent is then distilled from most of the extractant in the low-pressure stripping zone at 1.0-2.0 ata, the extractant is recycled to the upper part of the zone (s) of extractive rectification ation and intermediate desorbent in said at least (s) in terms of extractive distillation and 1,3-butadiene is further purified from impurities by distillation optionally in the presence of small amounts of extractant. 2. The method according to claim 1, characterized in that the polar solvent is selected from the group consisting of N, N-dimethylformamide, N-methylpyrrolidone, N, N-dimethylacetamide, N-formylmorpholine, sulfolane, methoxypropionitrile or mixtures thereof, possibly with water and said intermediate desorbent is selected from the group consisting of isopentane, n-pentane, pentenes, cyclopentane, hexanes, hexenes, cyclohexane and mixtures thereof. 3. The method according to claim 1, characterized in that butane (s) and butenes are separated from 1,3-butadiene in the composition of the distillate of the extractive distillation zone, for the most part of the separation elements of which the concentration of said extractant is maintained from 60 to 85 wt.%. 4. The method according to claim 1, characterized in that a steam stream including at least α-acetylene hydrocarbons, methylallene and an intermediate desorbent is withdrawn from the lower part of the high-pressure stripping zone (s), a part of the stream is concentrated and returned to the specified the desorption zone and the rest are removed from the system. 5. The method according to claim 1, characterized in that an additional amount of extractant is supplied to the upper part of the high-pressure stripping zone and its concentration on most separation elements is maintained at least 40 wt.%. 6. The method according to claim 1, characterized in that the temperature in the cube (s) of the zone (s) of extractive distillation is maintained from 90 to 140 ° C, in the cube (s) of the zone (s) of high pressure desorption zone from 120 to 170 ° C and in the cube distillation of the intermediate desorbent from the extractant from 120 to 170 ° C. 7. The method according to claim 1, characterized in that the purification of 1,3-butadiene from impurities of α-acetylenes With ₄ and methylallylene is carried out by distillation in the presence of a small amount of extractant, which is introduced into the upper part of the distillation zone and maintain its concentration on most separation elements from 15 to 40 wt.%. 8. The method according to claim 7, characterized in that C ₄ hydrocarbons are distilled off from the bottom residue of the specified rectification zone in the presence of a small amount of extractant, and the remaining part is sent to the specified high-pressure desorption zone directly or through its boiler. 9. The method according to claim 1, characterized in that prior to the supply of the initial hydrocarbon mixture to the extractive rectification zone, at least propine and other C ₃ hydrocarbons are separated by rectification. 10. The method according to claim 1, characterized in that prior to feeding the initial hydrocarbon mixture to the extractive rectification zone, it is possible, after rectification from at least propine and other C ₃ hydrocarbons, to catalytically hydrogenate butenine and partially other α-acetylene hydrocarbons to a residual content thereof butenin from 0.01 to 0.2 wt.%.

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